Base frame for a gas turbine

ABSTRACT

A base frame for a gas turbine and driven machinery such as generators and the like, includes a centrally arranged hollow section which acts as a torsion-absorbing body, sections or wings which extend from the hollow section and form an angle of approximately 90° with the longitudinal axis of the hollow profile, one or more plate-shaped bodies arranged to cover wholly or partly the hollow section and the sections, wherein between the plate-shaped bodies, the sections and the hollow section there is formed at least one chamber on each side of the longitudinal axis of the hollow section, in which chambers there are provided pull-out modules which can house operating and control systems for the gas turbine, and that the hollow section is in the form of a hollow section having a rectangular cross-section.

BACKGROUND OF THE INVENTION

The present invention relates to a base frame for a gas turbine andoptional driven machinery such as generators and the like, which baseframe includes a centrally arranged hollow section which acts as atorsion-absorbing body, sections or wings which extend from the hollowsection and form an angle of approximately 90° with the longitudinalaxis of the hollow section, one or more plate-shaped bodies arranged tocover wholly or partly the hollow section and the sections, wherebetween the plate-shaped bodies, the sections and the hollow sectionthere is formed at least one chamber on each side of the longitudinalaxis of the hollow section.

DESCRIPTION OF THE RELATED ART

Gas turbines and optional driven machinery such as, e.g., generators,are often mounted together on base frames. This is especially true inthe case of gas turbine installations on offshore oil platforms, wherethe gas turbine and the driven machinery can be mounted and dismountedas a unit. Around the gas turbine and the driven machinery there isusually provided an encasing housing having ventilation means or thelike to maintain the temperature inside the housing within a desiredrange.

In such installations the torque between the gas turbine and the drivenmachinery is absorbed by the frame. This requires a robust framestructure and a frame of this kind is usually constructed in a differentmanner than a frame where the gas turbine and the driven machinery arearranged on separate frames, in such manner that the frame is not toabsorb the torque.

In base frames which are to absorb torque, the frame is usually based ona round central tube which is to take up the torque or torsional forces.

A frame structure is known from inter alia EP 0 065 413, where a skidfor rotating machinery is taught, consisting primarily of atorque-absorbing body in the form a round central tube, a so-calledtorsion tube.

U.S. Pat. No. 4,572,474 teaches a method of mounting a rotating machineand driven machinery on a base frame. However, this frame does not havea centrally positioned torque-absorbing body.

A disadvantage of a round central tube of this kind is that it involvesthe base frame having a relatively high constructional height, and alsoa relatively high weight, as a consequence of the necessary dimension totake up a desired torque.

All the equipment for controlling the operation of the gas turbine, thelubricating oil systems and feed devices for the gas turbine fuel areusually positioned on the top of the base frame, inside the housing.This positioning of the control and feed devices is disadvantageous fromseveral points of view.

The fuel gas system is usually placed in an area in proximity to thehigh pressure turbine. If a blade becomes detached from the turbine, theblade will be thrown off and will penetrate the turbine housing and mayalso damage fuel gas valves and pipes. This may result in an explosionand fire.

A result of positioning the fuel gas system inside the housing is thatthe components are exposed to radiant heat from the turbine. This makesheavy demands on the temperature resistance of the components, whichmakes the fuel gas system more expensive.

In the event of an emergency shutdown of the turbine in a possible firesituation, the air dampers are usually closed preventing ventilation airfrom entering the housing, and the temperature inside the housing maythus increase to a level where cables and components are destroyed andwhere lubricating oil and hydraulic oil may convert to coke in thepipes.

In connection with fire classification of a turbine package, there arerequirements with respect to the maximum number of mechanical pipeconnections and joints. These requirements may be difficult to meet,because the pipe connections and joints must be welded, and this is alsodisadvantageous from a maintenance point of view.

Another major drawback with the conventional position of the fuel gasand lubricating oil systems is that there is no access for inspectionwhen the turbine is in operation.

SUMMARY OF THE INVENTION

The object of the present invention is primarily to solve theaforementioned problems.

Another object of the invention is to move the fuel gas system away fromthe area where it may be exposed to damage as a result of detachedturbine blades striking parts of the fuel gas system. The risk ofexplosion and fire is thus also reduced.

Another object of the present invention is to eliminate the temperatureproblems which may arise as a result of radiant heat from the turbineunder normal operations and especially the temperature problems whichmay occur as a result of an emergency shutdown of the turbine.

This is achieved with a base frame for a gas turbine and optional drivenmachinery such as generators and the like, which base frame includes acentrally arranged hollow section which acts as a torsion-absorbingbody, sections or wings which extend from the hollow section and form anangle of approximately 90° with the longitudinal axis of the hollowsection, one or more plate-shaped bodies arranged to cover wholly orpartly the hollow section and the sections, where between theplate-shaped bodies, the sections and the hollow section there is formedat least one chamber on each side of the longitudinal axis of the hollowsection, characterised in that in said chambers there are providedpull-out modules which can house operating and control systems for thegas turbine, and that the hollow section is in the form of a hollowsection having a rectangular, preferably square cross-section.

The chambers are preferably provided with rails and the modules areprovided with wheels or similar sliding or rolling devices whichinteract with the rails.

The chambers are preferably mechanically ventilated to a minimum of 90air changes per hour.

The operating and control systems which are arranged in the modules arepreferably connected to the gas turbine by means of quick releasecouplings.

The gas turbine and the driven machinery are located on the same baseframe, or they may be located on separate base frames.

The hollow section preferably extends throughout the entire length ofthe base frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail below, with the aid ofexemplary embodiments with reference to the accompanying drawings.

FIG. 1 shows a gas turbine with driven machinery placed on a frameaccording to the present invention.

FIGS. 2 and 3 are respectively a perspective view and an end view of abase frame according to the invention.

FIG. 4 shows a base frame according to the present invention.

FIGS. 5 and 6 show different arrangements of fuel gas and hydraulicunits according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a gas turbine 1, gear means 2 and driven machinery 3, e.g.,in the form of a generator, which are placed on a base frame, generallyindicated as 4. The gas turbine 1 is usually supported in three supportpoints 5, 6 and 7, respectively (FIG. 2). This is usually described as athree-point single lift skid.

The base frame 4 consists of a centrally located rectangular hollowsection 8, which runs throughout the entire length of the frame. The useof a rectangular hollow section instead of a round one results in lowerconstructional height and savings in weight in comparison with the knownbase frames.

From the hollow section 8 there extends a number of sections or “wings”9, which are secured to the hollow section 8 and form an angle ofapproximately 90° with the longitudinal direction of the hollow section8. The support points 5, 6, and 7 are secured to these sections or wings9.

One or more plates 10, 11 and 12, which wholly or partly cover the topof the base frame 4, are provided on top of the base frame 4. Thepurpose of these plates will be described in more detail below.

Between the wings 9 and the underside of the plates 10, 11 and 12 one ormore chambers 13 are formed on each side of the hollow section 8 whichcan provide space for different types of modules 15 see FIGS. 5-6.

These modules 15, which are intended to contain the operating andcontrol systems for the gas turbine, that is to say, the fuel gas andhydraulic systems, are provided with wheels or similar sliding orrolling devices to interact with the rails 14 provided in the bottom ofthe chambers 13. The purpose of this to allow the modules 15 very simplyto be pushed in and pulled out of the chambers for maintenance andinspection. Because the central torsion tube is in the form of arectangular hollow section 8, optimal space is obtained in the chambers13. The plate-shaped bodies 10, 11 and 12 which wholly or partly coverthe top of the base frame 4, at least in the area situated immediatelyabove the chambers 13, will protect the equipment that is placed in themodules 15. The plate-shaped bodies 10, 11 and 12 which preferablyconsist of steel plates, will, for example, be capable of preventingdetached turbine blades from penetrating into the chambers 13, so that aconsiderably better protection against fire and explosion is obtainedthan is the case with the solutions used today.

To prevent the equipment located in the modules 15 from being exposed toelevated temperatures, which may be harmful to the equipment, thechambers 13 are mechanically ventilated with the aid of an externalventilation device, and the air change in the chambers 13 is at least 90changes per minute.

FIG. 4 shows the actual base frame 4, corresponding to the frame shownin FIGS. 1-3, where the plates 10-12 and the chamber 13 have beenomitted.

FIGS. 5 and 6 show two embodiments of the base frame according to thepresent invention, on which there is mounted a gas turbine with drivenmachinery and hydraulic and fuel gas modules.

What is claimed is:
 1. A base frame for a gas turbine comprising: acentrally arranged hollow section which acts as a torsion-absorbingbody; wings which extend from the hollow section and form an angle ofapproximately 90° with a longitudinal axis of the hollow section, one ormore plate-shaped bodies arranged to cover wholly or partly the hollowsection and the wings, wherein between the plate-shaped bodies the wingsand the hollow section there is formed at least one chamber on each sideof the longitudinal axis of the hollow section, said chambers providedwith pull-out modules , the hollow section being in the form of a hollowsection having a rectangularly cross-section.
 2. The base frameaccording to claim 1, wherein: the chambers are provided with rails andthe modules are provided with wheels or sliding or rolling devices whichinteract with the rails.
 3. The base frame according to claim 1, whereinthe chambers comprise ventilators sized for mechanically ventilating thechambers to a minimum of 90 air changes per hour.
 4. The base frameaccording to claim 1, further comprising operating and control systemsarranged in the modules and connectable to a gas turbine by quickrelease couplings.
 5. The base frame according to claim 1, wherein thebase frame further comprises support points to mount a gas turbine and adriven machinery.
 6. The base frame according to claim 1, wherein thehollow section extends throughout the entire length of the base frame.7. The base frame of claim 1, wherein the hollow section has a squarecross-section.
 8. The base frame of claim 5, wherein the base framefurther comprises: a turbine mounted on the support points, and controlequipment mounted within at least one of the modules and operativelyconnected to the turbine.